High output alternator recommendations

s this because the battery provides some of the load/voltage/amperage?
No, simply because you may have a larger alternator than the loads. Which "you hope" is the case. Even when these cars were first built (with alternators) in the early days, 37A units, back then everything in the car except the starter would not be more than the 37A.

Which is why you need some kind of load that you can quantify, IE measure